The discovery of 51 Pegasi b, a planet orbiting a star in the constellation Pegasus (at left in this artist's concept), opened an astronomical gold rush. Astronomers began hunting for additional exoplanets in a big way. Their efforts have led to the discovery of more than 4,000 confirmed exoplanets and thousands more candidate worlds. 51 Pegasi was the first confirmed planet orbiting a star that is similar to the Sun. Astronomers Michel Mayor and Didier Queloz, who discovered 51 Pegasi, earned a share of this year's Nobel Prize in Physics for the find. [ESO/M. Kornmesser/Nick Risinger (skysurvey.org)]